Signal emitting styluses, e.g. active styluses are known in the art for use with a digitizer system. Position detection of the stylus provides input to a computing device associated with the digitizer system and is interpreted as user commands. In some known systems, position detection is only performed while the stylus tip is touching a detection surface of the digitizer system. In other known systems, position detection is also performed while the stylus tip is hovering over the detection surface. Typically, hover and touch input is interpreted differently. Often, the digitizer system is integrated with a display screen, e.g. to form a touch screen. Position of the stylus over the screen is correlated with virtual information portrayed on the screen.
Digitizer systems track free style input provided with a finger, conductive object. Optionally, digitizer systems also support tracking signal emitted by a stylus. A mutual capacitive sensor is one type of digitizer sensor for a digitizer system. Mutual capacitive sensors typically include a matrix formed with parallel conductive material arranged in rows and columns with a capacitive connection created around overlap and/or junction areas formed between rows and columns. Bringing a finger or conductive object close to the surface of the digitizer sensor changes the local electrostatic field and reduces the mutual capacitance between junction areas in the vicinity. The capacitance change at junctions on the grid is detected to determine location of the finger or conductive object on the capacitive sensor. The capacitance change is determined by applying a signal along one axis of the matrix while sampling output on the other axis to detect a coupled signal. Mutual capacitive detection allows multi-touch operation where multiple fingers, palms or conductive objects can be tracked at the same time.
A signal emitting stylus is typically detected and tracked by a digitizer system over a period that is not being used for mutual capacitive detection. A signal emitted by a stylus is typically detected and tracked by sampling output from both axes of the digitizer sensor to identify. Input detected on row and columns of the sensor is used to define coordinates of stylus interaction.